1. Field of the Invention
The present invention relates to a compact apparatus for the semi-automatic horizontal assembly of photovoltaic panels with solar cells of silicon; said apparatus being of the multi-function system type for experimental or laboratory use, with a high level of precision of the working and great versatility of use.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
The invention finds particular application in the industrial sector of photovoltaic panels with cells of crystalline silicon and is preferably, but not exclusively, intended for use in experimental research and development laboratories to easily carry out the assembly tests, the technological set-up, the tests and the qualifications of the new products with the same quality standards as a production system in its final and complete configuration. In more detail, the proposed apparatus is of the compact and multi-function type and substantially acts as a semi-automatic pilot system being structured as a single workstation equipped in such a way as to concomitantly carry out all the working processes provided for the assembly of a photovoltaic panel and repeat in an extremely small space the multiple operating phases which in an automatic production line are instead placed sequentially on separate workstations. Such a solution of a compact apparatus, therefore, is particularly versatile and is suitable for laboratory uses or for limited production volumes.
The proposed apparatus allows to assemble photovoltaic panels having cells of any type and size, also being suitable for panels of the evolved type called back-contact, which are also called of second generation to distinguish them from the conventional panels with front-contact and back-contact cells. Said back-contact panels are characterised by a multi-layer back support of the conductive type, which is conventionally called conductive backsheet, on which the innovative back-contact cells of silicon are mounted, which are generally placed in a matrix, by rows, to form panels for example having 48, 60 or 72 cells each. The invention allows to load such cells and contact them by means of conductive adhesives, of the type called ECA, said loading and said contacting being coordinated with each other and carried out concomitantly on the same working surface, in a precise and repeatable way, with the aid of optoelectronic control systems. On the same working surface one can also apply the layer of encapsulating material and the front glass.
Nowadays, in particular, one can consider as widely known the advantages provided by said photovoltaic panels with cells of the back-contact type; however, said panels are not very widespread yet due to realization difficulties which are mainly linked to the low availability of systems and of processes suitable for the current production standards, in particular with reference to the required precision in the loading and contacting of the cells, to product quality, to the automation of the systems and to industrial costs. Therefore, today the difficulties that can be found in the experimental phases of research and development aimed to the set-up of the product and of the technologies to be used in the automatic system that will produce it are even greater.
For the purpose of determining the prior art related to the proposed solution a conventional check was made, searching public archives, which has led to find some prior art documents, among which:
D1: US8485774 (Knoll et al.)
D2: W02008145368 (Reinisch et al.)
D3: DE102008046327 (Kalmbach et al.)
D4: W003098704 (Dings et al.)
D1 describes a high productivity system including a plurality of stringers which are arranged perpendicular to a transportation system that transfers them towards the central control and codification station before entering the adjacent interconnection station, where the complete matrix is formed, the system being controlled by a camera detection unit and managed by the central control system.
D2 describes an assembly station structured with two parallel working levels: an upper level for the cells and a lower level for the transparent glass, the preparation of the cells being separated into two adjacent tracks, which join each other to couple with the underlying glass in a laser welding station, the conveying devices being comprised in the overall dimensions of the aligned devices that form the production line.
D3 proposes a compact and versatile system for the assembly of photovoltaic panels having standard cells in a central station, grouping around it several devices having different functions: a support preparation device, two opposed devices for the pre-assembly of the cells, a device for the positioning of the transverse contacts on the substrate, a device for loading the pre-assembled cells, a device for the contacting between the cells, a device for closing the circuits of the strings and a device for fixing the components to the supporting glass.
D4 proposes a compact and versatile system for the production of photovoltaic panels having standard cells which is made up of four stations placed side by side in a crossed way where a first station is intended for the preparation of the cells, with an automated application of the conductive connecting elements both on the front and on the back of each cell, a second station is intended for the pre-assembly of the front glass with an upper layer of EVA, a third central station is for the stringing to form the matrix of cells directly on said glass translated to the centre, carrying out the contacting of the cells by welding or laser without contact, and a fourth final station where the protection layer is superimposed and the back electrical contacts of the panel are applied, and the panel is then rolled.
In conclusion it is reasonable to consider as known:                a continuous system for constructing panels with cells of the standard type and stringing carried out separately by means of welding, laser or induction;        a continuous system for constructing panels with cells of the back-contact type and contacting carried out directly on the conductive backsheet by means of a conductive adhesive in drops;        a system for panels having standard cells wherein, around the central assembly station, several devices having different functions are grouped;        a system for standard cells panels made up of four stations placed side by side in a crossed way, being respectively intended for the automated application of the conductive elements, for the pre-assembly of the glass with the EVA layer, for the complete stringing of the panel, for the superimposition of the back protection layer with the electrical contacts to form the panel ready for rolling.        
Drawbacks
In conclusion, we have observed that all the known solutions have drawbacks or anyway some limits.
In the first place, it has been observed that the difficulties typically noticeable in the experimental phases of research and development aimed to the set-up of the product and of the related technologies mainly derive from the need to test separately in laboratory the various working processes with which the photovoltaic panel will be industrially assembled, using the same technology, the same mechanisms, the same level of precision and repeatability. In particular, such difficulties are widely known to the companies that develop and produce panels of the back-contact type because the loading and the electrical contacting of said back-contact cells on the conductive backsheet require a high level of precision in the execution and are the cause of frequent faults in production, for example due to the misalignment of the points of contacting between the cells and the conductive layer of the backsheet or due to problems of welding or distribution and centring of the ECA conductive adhesive.
In more detail as to the above-mentioned difficulties, it has also been observed that the known and conventional solutions of industrial systems for the assembly of photovoltaic panels, such as D1 and D2, are not suitable for experimental activities of research and development, for example in the context of a laboratory, as they are designed to continuously carry out the specific working processes required by the panel being produced and they are also expensive and bulky; therefore, it has been observed that all the known and conventional solutions are little versatile in use when changes to the product or to the related production technologies are required. Furthermore, we have observed that the solutions which are more compact in size, such as D3 and D4, are expensive, bulky, little versatile and do not allow to assemble the new panels with back-contact cells. In particular, it is pointed out that nowadays versatile, compact, reliable apparatuses of high comfort of use are not available on the market for the purpose of carrying out concomitantly and in an integrated way the various working processes which can be performed while assembling a photovoltaic panel, repeating in a laboratory the same conditions and the same levels of precision and repeatability which are typical of a continuous system designed for high production volumes. However, said experimental apparatuses with high reliability and versatility of use are currently necessary in the phases of development of the products of the evolved type, such as in the case of said panels with back-contact cells, the phase of optimization and set-up of the production technologies and of the assembly method being particularly complex and expensive.
Secondly, it has been observed that the equipment conventionally pre-arranged to carry out in a laboratory the various assembly phases, for example the loading with automatic alignment of the cells or the drop-by-drop application of the adhesive ECA by means of the dispensing technology are constructively separate and diversified from each other and therefore require high investment costs, considerably increasing such costs every time new equipment is tested.
Thirdly, it has been observed that said separate and diversified equipment occupies large spaces, considerably increasing such spaces every time new equipment is adopted.
Fourthly, it has been observed that said separate and diversified equipment implies long times for the manual transfer of the panel for the purpose of carrying out a complete assembly cycle, considerably increasing such times every time a new operating phase is adopted in the cycle, but above all the risks of introducing faults due to the following rearrangements, modifications and movements.
Fifthly, it has been observed that by using separate and diversified equipment it is hard to detect and electronically integrate with each other the working processes carried out separately, for the purpose of simulating with discontinuous phases, on different equipment, an automatic assembly cycle of the continuous and integrated type.
Sixthly, it has been observed that the use in experimental phases of multiple separate and diversified equipment increases the risk of injury for the operators because they are not integrated with each other and also, sometimes, are little protected if self-constructed.
Moreover, it has been observed that the various devices and equipment used in the experimental phases of research and development are not standardized but constructed according to a specific project of the customer for the purpose of carrying out some working processes or operating phases which are related to a particular panel, and also to adapt to the site where said research activities are performed, for example a laboratory; such solutions, therefore, do not allow to be industrially reused in the production site for the purpose of being correctly integrated in an automatic system of the continuous type which is intended to assemble the panel with high production volumes, it not being possible to recover the initial investment for said experimental equipment.
Hence the need for companies of the sector to find solutions which are more effective with respect to the currently existing solutions; the aim of the present invention is also to solve the described drawbacks.